Dedicated CPT Drilling Rig and Seismic CPT Creates Demand

A desire for a dedicated CPT drilling rig to push cone and increased interest in seismic CPT (SCPT test) led Catawba Valley Engineering & Testing in North Carolina to add a 20CPT Press on skid steer to their fleet along with the Geoprobe^® seismic CPT system.

“We wanted a rig dedicated to pushing cone because it was taking time away from drilling with our other machines, and we wanted flexibility to use skid steer for other things when not using 20CPT Press,” said David M. Legrand Jr., PE, owner. “This will allow us to do more in situ exploration work.”

Having the dedicated CPT drilling rig for push types of projects not only increases their ability to take on more technical exploration projects because they offer multiple in situ exploration tools, but also makes their in situ investigations easier.

“I’m surprised by the greater push capability because of the anchoring versus running a conventional rig,” LeGrand said. “We’ve gained so much pushing thrust compared to our current rigs that you’ll break something if you’re not careful.”

He used the 20CPT Press on skid steer inside a Charlotte, North Carolina, warehouse pushing 30- to 80-foot supplemental SCPT test soundings to assist in foundation design. He anchored to the 5-inch slab in what had been a nuclear bomb manufacturing facility during World War II.

“With the combination of the press and the anchoring, we hit 1,000 tsf, which is near maximum cone tip pressure,” LeGrand said. “We were blown back by what we could push through that normally results in anchor refusal with our conventional rigs.”

Consultants are catching onto the additional abilities.

“We’re sought out for more technical in situ exploration projects,” LeGrand said. “It’s the best purchase out of the machine fleet. It’s compact, versatile switching in situ tooling. It’s great for getting into places a lot of others can’t, whether that’s up a loading dock, ramp, around a tight corner, or into a building.”

SEISMIC CPT (SCPT Test)

While 20CPT Press on skid steer has created demand, performing SCPT tests enables them to stay ahead of the curve.

“We added seismic because new proposed building codes in North Carolina will soon be requiring shear wave data and the practice is trending that way anyway,” LeGrand said.

He appreciates the innovation and support provided with the Geoprobe^® seismic CPT.

"I’m pleased to see how they’ve been continuously innovating the seismic to make things better,” LeGrand said. “They’re always listening to driller feedback. It’s taken into consideration when making new tooling or software improvements.”

While on a job in Wilmington, North Carolina, they were conducting a SCPT test in a swampy lowland in more than 100 degree heat.

“A wire wiggled loose. I text Cory [Harvey, CPT specialist], clearly stating not to feel obligated to answer since it was the weekend. He responded right back,” LeGrand said. “I can always get a clarifying conversation if not a resolution. It’s honestly a friendship to an extent as well. It’s about being professional and making money, but we’re all human beings."